The MMR vaccine is a mixture of live attenuated viruses, administered via injection for immunization against measles, mumps and rubella. It is generally administered to children around the age of one year, with a booster dose before starting school (i.e. age 4/5). It is widely used around the world; since introduction of its earliest versions in the 1970s, over 500 million doses have been used in over 60 countries. As with all vaccinations, long-term effects and efficacy are subject to continuing study. Before the widespread use of a vaccine against measles, its incidence was so high that patients born before 1949 are assumed to have had measles. Today the incidence of measles has fallen to less than one percent of people under the age of 30 in countries with routine childhood vaccination. Measles has a significant complication rate, which includes pneumonitis and encephalitis. There are a number of adverse effects listed in the product documentation for the MMR vaccine.